The present invention relates to a head for use in an ink jet printer and, more particularly, to a unique arrangement of a multi-nozzle head feasible for a so-called ink on-demand type ink jet printer in which ink compressing chambers constituting the head and electrostrictive vibrators in an information signal supply section also constituting the head are individually arranged in such a manner as to promote integration of the head.
Ink on-demand type ink jet printers have been extensively used due to their simple and, therefore, potentially small-size and economical construction, compared to charge control type and other various types of ink jet printers. Such a type of printer, in view of its inherently low drive frequency, is furnished with a multi-head configuration, or multi-nozzle configuration, in order to print out information at a high speed and with a high resolution. In a prior art ink jet printer of the type concerned, an electrostrictive vibrator forming essential part of an information signal supply section of a head is usually directly fit on a wall of an ink compressing chamber. Therefore, for a multi-head or multi-nozzle (integrated) configuration, it is a prerequisite that the ink compressing chambers be individually dimensioned as small as possible to enhance the degree of integration. However, because each electrostrictive vibrator is fixedly retained by a wall of its associated ink compressing chamber substantially along its entire circumference, decreasing the chamber dimensions renders the vibrator difficult to vibrate and, thereby, disenables the chamber to vary its volume by an amount which is necessary for ejection of ink drops. For this reason, the ink compressing chambers cannot be designed small beyond a certain limit to make the integration of heads quite difficult.
To solve this problem, elaborated arrangements of a plurality of ink compressing chambers have been proposed such as one in which the ink compressing chambers are shifted in position from each other, that is, they are arranged not in a direction perpendicular to a direction of ink drop ejection but with a given inclination. However, because the ink compressing chambers cannot be formed in a small size for the reason described above, such an implementation is impractical unless the ink passageway extending from each chamber to its associated nozzle is made longer. This would result in a bulky head construction and not in the desired integration.
In light of this, Takuro Isayama who is one of the inventors of the present invention has already proposed in U.S. patent application Ser. No. 481,066, filed Mar. 31, 1983 and West German patent application No. P 33 11 956.2, filed Mar. 31, 1983 a multi-nozzle head for an ink on-demand type ink jet printer which is unique in construction in that a signal supply section thereof has a cantilevered structure for the integration of a head.
The present invention constitutes an improvement over the multi-nozzle head with a cantilevered signal supply section proposed in the prior application for use in an ink on-demand type ink jet printer.